Lamps are used to illuminate signs, such as street signs, billboards, business signs, and the like. Many of these signs, however, are not easily accessible without special equipment. For example, in some instances a lift truck needs to be used to access the sign. Thus, if one or more of the lamps used to illuminate the sign were to burn out, it can be quite expensive to change the lamp(s).
Some lamp manufacturers have recognized this problem and have developed high reliability lamps or bulbs that have substantially longer lives than conventional lamps. For example, these long-life lamps can last about five to ten times longer than conventional lamps. Since high reliability lamps need to be changed less often, the added labor and equipment costs to change the lamps occur less often. However, high reliability lamps are much more expensive than conventional lamps.
Since many lamps are used outdoors, they are subject to temperature extremes. For example, in some environments the lamp can be subjected to extremely low outdoor air temperatures. Unfortunately, typical high reliability lamps do not emit as much light in relatively cold temperatures as compared to relatively warm temperatures. Thus, the added expense of these high reliability lamps may not be practical in some environments due to lack of light emitted in cold temperatures.
Conventional fluorescent lamps used in signs are long, linear tubes which inherently distribute light evenly over large areas. On the other hand, high reliability lamps are often compact tubes, which require reflectors to evenly distribute the output light over large areas.